There are three certainties in life: death, taxes and Arsenal keeping a clean sheet.
Mikel Arteta's side matched a 122-year club record on Tuesday night by doing so for the eighth game on the bounce in their Champions League win over Slavia Prague.
To their credit, the Czech side came out of the blocks like a house on fire, but after the 20-minute mark, the Gunners established control over the game that remained until the final whistle.
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However, while most of the team impressed, there was one player who looked off the pace and was far less effective than Mikel Merino.
Merino's night vs Slavia
With Viktor Gyokeres joining Kai Havertz and Gabriel Jesus on the injury list over the weekend, Merino was once again drafted in to start up top.
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Given the fact that the Czech giants hadn't lost a home game since December, it was always going to be a challenging evening for the makeshift number nine, and early on, it looked it.
However, just 35 seconds into the second half, the Spanish international once again found himself in the right place at the right time and buried a brilliant cross from Leandro Trossard.
It wasn't a lucky or scrappy goal, though; it was a well-timed run and a proper centre-forward's finish on the half volley.
With his name on the scoreboard, the 29-year-old seemed to grow in confidence and just 22 minutes later headed home his second from a Declan Rice delivery.
He did more than bag a brace, though, as in his 95 minutes of action, he played one key pass, took 52 touches, covered 10.2km, made three interceptions, two clearances and three recoveries.
It really was a man-of-the-match display from Merino and one that should fill Arteta with confidence ahead of a tricky game away to Sunderland on Saturday.
Mikel Merino stats Slavia Prague vs Arsenal
However, there was another starter who more than likely played himself out of the team.
Arsenal's underwhelming star
Unfortunately, while the likes of Merino, Trossard and Rice were looking brilliant against Slavia, Ethan Nwaneri was not.
Now, there is no denying that the 18-year-old is an extraordinarily talented prospect and someone who still seems destined for big things.
However, it is also true that he was the most underwhelming player for the Gunners on Tuesday night and looked like an inexperienced youngster.
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For example, while he did get himself into promising areas on several occasions, he'd then either lose the ball, play the wrong pass or hold on to it for too long.
As content creator Alex Moneypenny points out, the Hale Ender will have to "prioritise retention" more if he "wants to go to the next level."
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It might sound harsh, but the Sun's Chisanga Malata was also unimpressed, awarding the teen a 5/10 match rating and writing that he "was anonymous in the first half and struggled to get into the game."
Unfortunately, his statistics more than back up such an appraisal, as in 65 minutes he amassed a combined expected goal and assists figure of just 0.04, failed to complete a single cross, took 30 touches - 18 fewer than David Raya - completed just 18 passes, lost possession six times and won two of seven duels.
Nwaneri's game vs Slavia
Minutes
Expected Goals
Goals
Expected Assists
Assists
Crosses (Accurate)
Accurate Passes
Touches
Lost Possession
Tackles (Won)
Ground Duels (Won)
Aerial Duels (Won)
Fouls
All Stats via Sofascore
Ultimately, Nwaneri is an incredible talent and will surely get back to his best this season, but due to his poor performance against Slavia, he should be dropped for the Sunderland game.